High piezoelectric-magnetic coupling in potassium-sodium niobate piezoelectric ceramics prepared by solution synthesis

Abstract

BiFeO3 is a multiferroic material that is difficult to synthesize by conventional solid-reaction methods. In this work, high piezoelectric-magnetic coupling was realized in a (1−x)(K0.5Na0.5)NbO3−xFe2O3 piezoelectric ceramic synthesized by combining solution synthesis and a conventional solid-reaction method. The remanent magnetization (Ms of ∼150 memu/g and Mr of ∼43 memu/g at 20 kOe) and remanent polarization (Pr of ∼8.12 μC/cm2) were achieved simultaneously for the 0.8KNN–0.2Fe2O3 ceramic, which were considerably higher than those of reported perovskite-type multiferroelectric ceramics and BiFeO3 obtained by the conventional solid-reaction method. This high piezoelectric-magnetic coupling was ascribed to the interplay of KNN and Fe2O3, which improved the magnetic performance by increasing the spin charge density and exchange-coupling-mediated electrically driven magnetization. Furthermore, the (1–x)(K0.5Na0.5)NbO3–xFe2O3 ceramics possessed higher piezoelectric constants (d33 = 80–115 pC/N) than KNN because appropriate Fe2O3 formed smaller domains even at the nanoscale, thereby enhancing Pr. Therefore, this study provides an alternative strategy for the synthesis of perovskite-type multiferroelectric ceramics with high piezoelectric-magnetic coupling to meet the increasing miniaturization and functional requirements of electronic components.